 /*******************************************************************************
  * Copyright (c) 2000, 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.update.internal.core;
  
 /**
  * <code>Assert</code> is useful for for embedding runtime sanity checks
  * in code. The static predicate methods all test a condition and throw some
  * type of unchecked exception if the condition does not hold.
  * <p>
  * Assertion failure exceptions, like most runtime exceptions, are
  * thrown when something is misbehaving. Assertion failures are invariably
  * unspecified behavior; consequently, clients should never rely on
  * these being thrown (or not thrown). <b>If you find yourself in the
  * position where you need to catch an assertion failure, you have most
  * certainly written your program incorrectly.</b>
  * </p>
  */
 public final class Assert {
     
     /**
      * <code>AssertionFailedException</code> is a runtime exception thrown
      * by some of the methods in <code>Assert</code>.
      * <p>
      * This class is not declared public to prevent some misuses; programs that catch
      * or otherwise depend on assertion failures are susceptible to unexpected
      * breakage when assertions in the code are added or removed.
      * </p>
      */
     private static class AssertionFailedException extends RuntimeException {

         private static final long serialVersionUID = 1L;

         /**
          * Constructs a new exception.
          */
         public AssertionFailedException() {
         }
         
         /**
          * Constructs a new exception with the given message.
          */
         public AssertionFailedException(String detail) {
             super(detail);
         }
     }
 /* This class is not intended to be instantiated. */
 private Assert() {
 }
 /**
  * Asserts that an argument is legal. If the given boolean is
  * not <code>true</code>, an <code>IllegalArgumentException</code>
  * is thrown.
  *
  * @param expression the outcome of the check
  * @return <code>true</code> if the check passes (does not return
  * if the check fails)
  * @exception IllegalArgumentException if the legality test failed
  */
 public static boolean isLegal(boolean expression) {
     // succeed as quickly as possible
 if (expression) {
         return true;
     }
     return isLegal(expression, "");//$NON-NLS-1$
 }
 /**
  * Asserts that an argument is legal. If the given boolean is
  * not <code>true</code>, an <code>IllegalArgumentException</code>
  * is thrown.
  * The given message is included in that exception, to aid debugging.
  *
  * @param expression the outcome of the check
  * @param message the message to include in the exception
  * @return <code>true</code> if the check passes (does not return
  * if the check fails)
  * @exception IllegalArgumentException if the legality test failed
  */
 public static boolean isLegal(boolean expression, String message) {
     if (!expression)
         throw new IllegalArgumentException (message);
     return expression;
 }
 /**
  * Asserts that the given object is not <code>null</code>. If this
  * is not the case, some kind of unchecked exception is thrown.
  * <p>
  * As a general rule, parameters passed to API methods must not be
  * <code>null</code> unless <b>explicitly</b> allowed in the method's
  * specification. Similarly, results returned from API methods are never
  * <code>null</code> unless <b>explicitly</b> allowed in the method's
  * specification. Implementations are encouraged to make regular use of
  * <code>Assert.isNotNull</code> to ensure that <code>null</code>
  * parameters are detected as early as possible.
  * </p>
  * Method throws an unspecified unchecked exception if the object
  * is <code>null</code>
  * @param object the value to test
  */
 public static void isNotNull(Object object) {
     // succeed as quickly as possible
 if (object != null) {
         return;
     }
     isNotNull(object, "");//$NON-NLS-1$
 }
 /**
  * Asserts that the given object is not <code>null</code>. If this
  * is not the case, some kind of unchecked exception is thrown.
  * The given message is included in that exception, to aid debugging.
  * <p>
  * As a general rule, parameters passed to API methods must not be
  * <code>null</code> unless <b>explicitly</b> allowed in the method's
  * specification. Similarly, results returned from API methods are never
  * <code>null</code> unless <b>explicitly</b> allowed in the method's
  * specification. Implementations are encouraged to make regular use of
  * <code>Assert.isNotNull</code> to ensure that <code>null</code>
  * parameters are detected as early as possible.
  * </p>
  * An unspecified unchecked exception is thrown if the object
  * is <code>null</code>
  * @param object the value to test
  * @param message the message to include in the exception
  */
 public static void isNotNull(Object object, String message) {
     if (object == null)
         throw new AssertionFailedException("null argument;" + message);//$NON-NLS-1$
 }
 /**
  * Asserts that the given boolean is <code>true</code>. If this
  * is not the case, some kind of unchecked exception is thrown.
  *
  * @param expression the outcome of the check
  * @return <code>true</code> if the check passes (does not return
  * if the check fails)
  */
 public static boolean isTrue(boolean expression) {
     // succeed as quickly as possible
 if (expression) {
         return true;
     }
     return isTrue(expression, "");//$NON-NLS-1$
 }
 /**
  * Asserts that the given boolean is <code>true</code>. If this
  * is not the case, some kind of unchecked exception is thrown.
  * The given message is included in that exception, to aid debugging.
  *
  * @param expression the outcome of the check
  * @param message the message to include in the exception
  * @return <code>true</code> if the check passes (does not return
  * if the check fails)
  */
 public static boolean isTrue(boolean expression, String message) {
     if (!expression)
         throw new AssertionFailedException("assertion failed; "+message);//$NON-NLS-1$
 return expression;
 }
 }



